How to stop a mosquito bite from itching

Cold is the fastest thing that works: ten minutes of a cold pack blunts the itch within seconds and can be repeated as often as you like. After that, hydrocortisone 1% on the bite or a non-drowsy antihistamine tablet, and — the part everyone skips — keeping your nails off it. Most mosquito bites stop itching within a day or two whatever you do; the goal is getting through those two days without breaking the skin.

In order of how much they do

1. Cold. A cold pack or a cold wet cloth for about ten minutes. It works immediately, costs nothing, and has no ceiling on repeats. Do not put ice directly on skin.
2. Stop scratching. Scratching feels like relief and buys about a minute, at the cost of a longer-lasting, more inflamed bite and a real chance of infection. Short nails, and a plaster or dressing over a bite you keep returning to.
3. Hydrocortisone 1%. A thin film on the bite, up to three or four times daily, up to seven days.
4. An oral antihistamine. More useful when there are several bites than for one, and at night when the itch is what is keeping you awake.
5. Calamine or colloidal oatmeal. Soothing rather than powerful, and fine to use freely alongside the rest.

Why it itches more at night

Two things stack. Body temperature rises slightly in the evening, which increases blood flow to the skin and amplifies the itch; and there is nothing else competing for your attention. Neither is imaginary, and both are reasons to treat the bite before bed rather than at three in the morning.

Things sold or suggested for this that are worth knowing about

• Topical antihistamine creams — widely sold, generally advised against. Antihistamine on skin can sensitise it, producing a rash worse than the bite.
• Benzocaine and other topical anaesthetics — numb briefly, and are a recognised cause of contact allergy with repeated use.
• Heat pens and thermal bite devices — apply a brief burst of heat around 50 °C. Some people report relief; the published evidence is thin and mixed, and they should not be used on children or on anyone who cannot report a burn.
• Household remedies — toothpaste, vinegar, baking soda, banana peel. Harmless in most cases, unsupported by evidence, and mostly working by the same cooling and distraction that a cold pack does more reliably.

When it is not just itch

A mosquito bite that keeps getting worse after two or three days rather than better is behaving unusually. Spreading warmth, increasing pain, pus, a red streak running away from the bite or fever means infection and needs assessing. Swelling of the face, lips or throat, wheeze or dizziness after any bite is an emergency.

And if the itch is spreading to places nothing bit, or is worst at night across wrists, waist and between the fingers, consider whether these are mosquito bites at all — scabies and bed bugs are both routinely mistaken for them.